People are increasingly utilizing Local Area Networks (LANs) in their residences to connect devices residing in disparate rooms within their residences. In addition, companies are also looking at utilizing LANs within vehicles to enable passengers to access information or entertainment while in a vehicle. The presence of LANs in a residential arena provides the opportunity to utilize this distribution network for non-traditional LAN applications. One such application is LAN audio. With the widespread presence of digital audio material, for example Moving Pictures Experts Group Layer-3 (MP3), LANs become an excellent transport network for the distribution of audio material throughout the home.
Current residential audio distribution systems typically take one of two following forms, excluding placing standard audio wiring throughout the home. The first system uses wireless technology to provide a tetherless connection between an audio source and a headset, or a speaker system. This type of system does not support multiple simultaneous audio programs on the system, and is generally not designed as a network distribution system but instead is intended to eliminate the need for wires or wiring. In addition, the wireless interface is typically integrated with the end-user device. The second system uses the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite to distribute audio over a LAN. This is typically implemented with an audio server as a source device, and a personal computer with an audio card as the end device. Internet Protocol (IP) multicast is used along with Realtime Transport Protocol (RTP) to enable end devices to join a multicast service. RTP is an Internet Engineering Task Fork (IETF) standard for streaming realtime multimedia over IP in packets. It supports transport of realtime data like interactive voice and video over packet switched networks. Within the RTP protocol, currently only a single audio program and audio encoding type is supported per multicast stream. Therefore to support multi-program audio, multiple multicast streams must be created with each stream supporting a separate audio program and potentially audio encoding type. The user would, at the end device, select the desired multicast stream from the group of multicast audio programs. This also means that the end device must learn or acquire the addresses of all of the multicast streams.
Therefore, it is desirable to provide a method and system which distributes multi-program audio over a network such as, for example, LAN within a single multicast stream, and which supports multiple audio encoding types.